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Avian colibacillosis, caused by avian pathogenic Escherichia coli (APEC), is one of the major infectious diseases of poultry that bring about great economic loss for the Bangladesh poultry industry. The present study aimed to determine the virulence genes of avian pathogenic Escherichia coli (APEC) from cases of colibacillosis in poultry at the Noakhali district of Bangladesh. Currently, virulence-associated gene profiles of APEC isolates were investigated by polymerase chain reaction (PCR). A total of 24 (twenty-four) Escherichia coli isolates were collected and presumptively identified from 8 (eight) colibacillosis cases from 4 commercial broiler poultry farms (2 broilers per farm) in Noakhali, Bangladesh. The pathogenesis of Escherichia coli involves a wide range of different virulence genes. At this point, four virulence genes, iutA, hlyF, iroN, and iss were detected by PCR analysis. It has been observed that iutA, iss, hlyF, and iroN genes were found in 7(29.16%), 20(83.33%), 22(91.66%), and 24(100%) APEC isolates respectively. Furthermore, out of the twenty-four APEC isolates, six (25%) isolates had four virulence genes, fourteen (58.33%) isolates carried at least three virulence genes, three (12.5%) isolates carried two genes and one (4.16%) isolates had one virulence gene. Most importantly. six types of virulence gene profiles existed within the APEC isolates from which profile number 3 (hlyF, iroN, iss) having 13 (54.16%) isolates were predominant. The occurrence of APEC isolates of this region which is responsible for avian colibacillosis cases can be a matter of concern from the public health point of view. Future investigations will be able to utilize these virulence genes to identify APEC in Bangladesh helping in the diagnosis and prevention of colibacillosis in poultry. Bioresearch Commu. 7(1): 967-972, 2021 (January)

A significant limitation to flourish poultry industry in Bangladesh is the emergence of multidrug resistance pathogenic bacteria like Salmonella spp. due to uncontrolled use of antibiotics for disease treatment. An alternative to antibiotics could be the application of probiotics. About 120 cloacal-swabs from poultry birds were investigated, seventy two (72) isolates of Salmonella spp. and twenty two (22) isolates of lactic acid bacteria (out of 50)were identified respectively by cultural, morphological and biochemical tests presumptively. Antibiotic sensitivity test of Salmonella spp. was performed, followed by Kirby-Bauer disc-diffusion assay with six antibiotic groups. All those isolates of Salmonella spp. were found to be highly resistant to â-lactam, cephalosporin, tetracycline and macrolide, highly sensitive to carbapenem and moderately sensitive to aminoglycosides. Then Salmonella spp. were used as a target for the prospective probiotic bacteria which were screened based on antimicrobial activity against those multidrug resistance Salmonella spp. In antagonism assay such as disc diffusion and one-streak method, it was revealed that five lactic acid bacteria showed antimicrobial activity against Salmonella spp. Further, lactic acid bacteria were characterized based on their tolerance ability to pH and NaCl, antibiotic susceptibility test. The tolerance range of Lactic acid bacteria was about pH (3.5-9.5), NaCl (4-8) % and also resistant to antibiotics groups like B lactam, aminoglycosides, and quinolone. Then 16S rDNA gene sequence analysis was performed for molecular identification of potential probiotic bacteria. One representative isolate was identified as phylogenetically closed relative to Pediococcus acidilactici. This study was able to demonstrate that Pediococcus acidilactici as anindigenous probiotic candidate to inhibit the growth of isolated multidrug resistant Salmonella spp. in poultry. The potent probiotic candidate Pediococcus sp. could be used to counter bacterial diseases in poultry, thereby it could ensure food safety in the poultry industries of Bangladesh. Bangladesh J Microbiol, Volume 34 Number 2 December 2017, pp 83-90